Photographic copying apparatus stripping mechanism



PHOTOGRAPHIC COPYING APPARATUS STRIPPING MECHANISM Filed Sept. 21, 1965 United States Patent Ofifice 3,348,839 Patented Oct. 24, 1967 3 Claims. (or. 271-64) The present invention relates in general to improved copying apparatus and more particularly to an improved mechanism in such apparatus for separating an exposed lightsensitive sheet, or a radiation-sensitive sheet generally, and an image-receiving sheet contacting each other in moistened relationship.

In United States patent application No. 361,728, now Patent Number 3,266,797, a mechanism has been described for separating an image-Wise exposed sheet material from an imagereceiving sheet material adhering thereto, wherein the leading edge of one material precedes the leading edge of the other material, said mechanism comprising means for making the preceding material to curve in a direction away from the other material and rubbing means operable to exert a rubbing action generally across the back side of the said other material, whereby this other material is forced to curl towards its back side so as to separate it from the preceding material.

Since in practice the application of the said mechanism is done in such a way that the rubbing action is exerted on the back side of the image-receiving material, because the leading edge of this material is then located backwardly with respect to the other material and thus may contact over its entire surface the surface of the other material, some difiiculties are met which are due to the curling tendency of the image-receiving material after drying.

Now has been found that the exertion of a rubbing action on the back side of the image-receiving material may be omitted When means for gripping the leading edge of the preceding sheet and means for submitting both sheets to a sudden change in movement directed towards the non-gripped sheet are provided.

An advantage of the mechanism according to the present invention is that it is suitable for separating a sheet of lightsensitive material from a sheet of image-receiving material, not only when both sheets are moistened by the processing liquid prior to their being pressed together, but also when only the sheet of light-sensitive material is moistened by the processing liquid and even when the processing liquid, necessary for accomplishing the imagetransfer, is only present between the contacting faces of both sheets adhering to each other.

In the two latter cases but a small quantity of processing liquid is employed which gives rise to the important advantage that the prepared copy is dry or almost so after separation.

The mechanism according to the present invention is particularly well-suited for application in cooperation with photographic copying apparatus for preparing copies according to the known silver halide diffusion transfer process.

According to this process, a light-sensitive material containing a silver halide emulsion layer is image-wise exposed to an original and pressed on an image-receiving material in the presence of a processing liquid, a developer and a silver halide complexing agent, whereby the unexposed and undeveloped parts of the silver halide are complexed and diffuse to the image-receiving material where they are converted into a silver image by the action of developing nuclei.

In the preceding introduction to this specification, it has been stated that the present invention is concerned with the separation of a light-sensitive material, or a radiation-sensitive material generally, from an image-receiving material. By the denotion material is not only meant distinct individual sheets, but also web-like materials which are cut into sheets prior to separation.

An exemplary embodiment of the invention will now be explained by the following detailed description read in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic side-view of a copying apparatus, combined with a separation mechanism according to the present invention, in non-operative position, and

FIG. 2 is a diagrammatic side-view of the separation mechanism according to FIG. 1, in operative position.

The copying apparatus represented in FIG. 1 is an apparatus of the known type which is provided with a roller applicator system for applying processing liquid to an image-wise exposed sheet of light-sensitive material and a pressure system for pressing the moistened sheet of light-sensitive material on a sheet of image-receiving material so that the diffusion transfer may take place.

The apparatus 1% contains an applicator roller 11, two

' squeegee rollers 12 for removing superfluous processing liquid from the sheet of light-sensitive material and two pressure rollers 13 for pressing the moistened sheet of light-sensitive material on the dry sheet of image-receiving material.

The exposed sheet of light-sensitive material follows a path marked by the broken line 14 and is introduced into the apparatus with its emulsion side directed downwardly. The sheet of image-receiving material follows a path marked by the dot and dash line 15 and is introduced into the apparatus with its image-receiving side directed upwardly.

On departure from the exit of the apparatus, both sheets pressed against each other are guided between two parallel guide plates 16 which are hingeable around a point 17. By a spring system (not represented) the guide plates are restrained in their highest position as shown in FIG. 1. By the energizing of a solenoid 18, the vertically displaceable core of which is connected to the set of guide plates 16, the latter are capable of hinging to a lower situated position as shown in FIG. 2.

After the guide plates 16 a driven pressure roller pair 19 is solidly mounted having the same peripheral speed as the squeegee rollers 12 and the pressure rollers 13'. In their central part the pressure rollers 19 are provided with opposite narrow grooves marked in broken lines. The lever 20 actuating the microswitch 21 extends in these grooves. The lever 20 is lightly movable and is urged by a non-represented spring into the position shown in FIG. 1. The lever can be pushed away very easily by the leading edge of a sheet which is transported by the rollers 19 and after a displacement of about 1 mm. it causes the lever of the microswitch 21 to drop so that the electric circuit of the solenoid 18 is closed.

The apparatus is further provided with the guide plates 22 and 23.

The apparatus is operated as follows: a sheet of imagereceiving material and a sheet of light-sensitive material, which is a few centimetres longer than the sheet of imagereceiving material, are introduced into the apparatus 10 by the operator.

Previously the operator has made the leading edges of both sheets coincide when introducing them into the apparatus. The operator keeps the ends of both sheets against each other and continues pushing on until sheets are gripped by the pressure rollers 13.

The sheet of light-sensitive material is moistened during its advancing over the applicator roller 11, which rotates at a peripheral speed being a multiple of the peripheral speed of the other rollers and which takes up processing liquid from a small trough to which said liquid is supplied from a container of greater dimensions, and in which said liquid is maintained to a constant level by known means.

Between the squeegee rollers .12 the superfluous liquid.

is pressed away from the sheet of light-sensitive material and the pressure rollers 13 press this sheet on the sheet of image-receiving material.

The path 15 followed by the sheet of image-receiving material when passing through the apparatus is somewhat longer than the path 14 followed by the sheet of light-sensitive material, so that the leading edge of the sheet of light-sensitive material precedes the leading edge of the sheet of image-receiving material by a distance of about 1.5 cm.

Both sheets pressed on each other are advanced between the guide plates 16 by means of the pressure rollers 13. When the leading edge of the preceding sheet of lightsensitive material is gripped by the rollers 19 and pushes the lever 20 away, the circuit of the solenoid 18 is closed by the dropped electric contact of the microswitch 17. The guideplates 16 are pulled downwardly thus giving rise to the appearance of the following phenomena.

The sheet of light-sensitive material is curved with its back side through a very sharp angle around the front edge 25 of the upper plate of the guide plates 16. The sheet of image-receiving material pressed on the sheet of light-sensitive material is not capable of following said sharply curved path and hence its leading edge, which at that moment is positioned at the locus of the front edge of the guide plates 16, releases from the other sheet and is not curved.

Further, due to the sudden pressing of the front part 25 of the said upper guide plate against the back side of the sheet of light-sensitve material, this sheet is stretched a little at that area, whereby the releasing of its leading edge from the leading edge of the sheet of image-receiv ing material,,almost lying in that place, is still particularly enhanced.

The further movement of both sheets is done along separated paths as is seen on FIG. 2. The advancing of the sheet of light-sensitive material occurs by means of the pressure rollers 19 which transport same over a guide plate 22, whereas the advancing of the sheet of imagereceiving material occurs by its adhering to the sheet of light-sensitive material. The sheet of image-receiving material, which moves straight forwardly for the reason set forth above, is conveyed between the guide plates 23. Owing to the omittance of any rubbing action and any sharp curvature, the sheet ofimage-receiving material will show no tendency to curl after drying.

The separating mechanism described hereinbefore can also be provided with additional roller pairs for further transporting the sheet of image-receiving material after leaving the guide plates 23, with a heating system for accelerating the drying of the sheet of image-receiving material before it leaves the apparatus, with intermediate drive rollers between the roller pairs 13 and 19 in case the path between the guide plates 16 is so long (e.g. to assure a sufficient time for the diffusion transfer process to take place) that the trailing edge of the sheets would have left the roller pair 13 before the leading edge of the preceding sheet would be gripped by the rollers 19, etc.

Finally, the separating mechanism can be combined with copying apparatus other than the described copying apparatus 10. However, care must be taken that one sheet always precedes the other-in the present embodiment the sheet of light-sensitive material precedes the sheet of image-receiving material-before both sheets are pressed on each other in the presence of liquid.

We claim:

1. Mechanism for separating in moistened state an exposed sheet of light-sensitive material and a sheet of image-receiving material wherein the leading edge of one sheet slightly precedes the leading edge of the other sheet, with means for gripping the leading edge of the preceding sheet, said mechanism comprising means suitable for pressing in operative position broadwise on the back side of the preceding sheet at a locus situated close to the gripping area of the said means for gripping the sheet to make both sheets execute in said area a sudden change of movement towards the non-gripped sheet so that, owing to the tendency of the non-gripped sheet to abstain from following the imposed curvature and due to the stretching of the gripped sheet, and its subsequent displacement thereof with respect to the non-gripped sheet, the leading edge of the non-gripped sheet will separate from the gripped sheet, and means for receiving the non-gripped sheet after its separation from the other sheet and for guiding the non-gripped sheet during its further advancing along a path which isditferent from the path followed by the gripped sheet.

2. Mechanism according to claim 1, in which the means for gripping the leading edge of the preceding sheet is formed by driven pressure rollers, the means suitable for pressing on the back side of the preceding sheet is formed by the front edge of a movable guide plate which guides the sheets, and the means for receiving the non-gripped sheet is formed by a guideplate one end of which terminates close to the position, taken by the said front edge of the movable guide plate'during the operative position of the separating mechanisrm:

3. Mechanism according to claim 1, comprising means to detect the gripping of the leading edge of the preceding sheet and, as a consequence thereof, to actuate the means which are suited to make both sheets execute a sudden change in movement.

References Cited UNITED STATES PATENTS 1/1962 Stuckens 271-64 8/1966 Stievenart 27164 

1. MECHANISM FOR SEPARATING IN MOISTENED STATE AN EXPOSED SHEET OF LIGHT-SENSITIVE MATERIAL AND A SHEET OF IMAGE-RECEIVING MATERIAL WHEREIN THE LEADING EDGE OF ONE SHEET SLIGHTLY PRECEDES THE LEADING EDGE OF THE OTHER SHEET, WITH MEANS FOR GRIPPING THE LEADING EDGE OF THE PRECEDING SHEET, SAID MECHANISM COMPRISING MEANS SUITABLE FOR PRESSING IN OPERATIVE POSITION BROADWISE ON THE BACK SIDE OF THE PRECEDING SHEET AT A LOCUS SITUATED CLOSE TO THE GRIPPING AREA OF THE SAID MEANS FOR GRIPPING THE SHEET TO MAKE BOTH SHEET EXECUTE IN SAID AREA A SUDDEN CHANGE OF MOVEMENT TOWARDS THE NON-GRIPPED SHEET SO THAT, OWINGM TO THE TENDENCY OF THE NON-GRIPPED SHEET TO ABSTAIN FROM FOLLOWING THE IMPOSED CURVATURE AND DUE TO THE STRETCHING OF THE GRIPPED SHEET, AND ITS SUBSEQUENT DISPLACEMENT THEREOF WITH RESPECT TO THE NON-GRIPPED SHEET, THE LEADING EDGE OF THE NON-GRIPPED SHEET WILL SEPARATE FROM THE GRIPPED SHEET, AND MEANS FOR THE OTHER SHEET AND FOR SHEET AFTER ITS SEPARATION FROM THE OTHER SHEET AND FOR GUIDING THE NON-GRIPPED SHEET DURING ITS FURTHER ADVANCING ALONG A PATH WHICH IS DIFFERENT FROM THE PATH FOLLOWED BY THE GRIPPED SHEET. 